Choosing POP or IMAP for your MobileMe email
Summary
The way you read, save, and organize your MobileMe Mail is determined by the protocol you choose when you set up your email account. By default, your MobileMe Mail account uses Internet Mail Access Protocol (IMAP) to retrieve your messages in an email client application such as Mac OS X Mail or Microsoft Outlook. Accounts created prior to the MobileMe transition can also use Post Office Protocol 3 (POP or POP3). The protocol that you should choose when setting up your MobileMe Mail account depends on how you prefer to access and read your email. This article explains the benefits of each protocol and tells you how to set up your account for whichever protocol you choose.
Note: The ability to use POP3 is disabled by default for MobileMe accounts created on or after 7/10/2008. IMAP is preferred as the default protocol for MobileMe email accounts since it allows you to access and manage your email from multiple computers using a mail application or browser, or an iPhone or iPod touch. If you would like to use POP3 with an existing (.Mac) email account, you can contact MobileMe Support and request that POP3 access be enabled.
Products Affected
MobileMe
IMAP
The IMAP protocol allows you to view the messages on your account without removing them from the server. You can also create folders on the server and organize messages within them. This is very useful if you need to check your account from more than one computer or from a web browser using MobileMe Mail. Since IMAP does not remove messages from the server unless you delete them, the messages are available to you from whichever computer or mobile device you use to check your mail. Another advantage of IMAP is each messages read/unread status is stored on the server, whereas with POP each message is considered unread when you access your account from a different application or computer. Any changes you make to your mail will be stored on the server, so if you read a message or mark it for follow up on one computer, those changes are reflected everywhere else. Your account stays in sync anywhere you go.
In Mac OS X Mail, the MobileMe account type (IMAP) is used by default when setting up a MobileMe email account. The MobileMe account type is IMAP with certain settings already configured.
If you want to save and organize your email on the server, to make it easier to read and manage your email from several different computers, you should use IMAP.
POP
The POP3 protocol downloads new messages from the server to your computer. It can sometimes be configured with options such as leaving a copy of the message on the server or downloading only messages that are less than a certain size, but POP3 is primarily intended to copy your mail messages from the server to your computer and either delete them immediately from the server, or after a period of time that you specify in the email application, such as after 30 days.
If you always use the same computer to read your email, and you do not want to store your mail on the server so you can access it from other computers or devices, then you may want to consider using POP.